Common O2 sensor trouble?
 

I keep getting CEL on my 92 civic Si. Compression test, new plugs, and of course new O2sensor. Acceleration boggs down during low rpms but once that vtec silenoid kicks in around 3 or 4rpms, it takes off. My buddy's 92 civic si had the same problem w the O2 code and just replaced the ECU and it worked. We swapped ECU's and i still have the same problem and his is OK. what gives????